This is a note to let you know that I've just added the patch titled
file: Implement task_lookup_fd_rcu
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
file-implement-task_lookup_fd_rcu.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3f3708f566736fa1cfa783187da901a6cbcde952
Author: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Date: Fri Nov 20 17:14:28 2020 -0600
file: Implement task_lookup_fd_rcu
[ Upstream commit 3a879fb38082125cc0d8aa89b70c7f3a7cdf584b ]
As a companion to lookup_fd_rcu implement task_lookup_fd_rcu for
querying an arbitrary process about a specific file.
Acked-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
v1: https://lkml.kernel.org/r/20200818103713.aw46m7vprsy4vlve@wittgenstein
Link: https://lkml.kernel.org/r/20201120231441.29911-11-ebiederm@xxxxxxxxxxxx
Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/file.c b/fs/file.c
index 6149f75a18a66..60a3ccba728cd 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -911,6 +911,21 @@ struct file *fget_task(struct task_struct *task, unsigned int fd)
return file;
}
+struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd)
+{
+ /* Must be called with rcu_read_lock held */
+ struct files_struct *files;
+ struct file *file = NULL;
+
+ task_lock(task);
+ files = task->files;
+ if (files)
+ file = files_lookup_fd_rcu(files, fd);
+ task_unlock(task);
+
+ return file;
+}
+
/*
* Lightweight file lookup - no refcnt increment if fd table isn't shared.
*
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 695306cc5337a..a88f68f740677 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -110,6 +110,8 @@ static inline struct file *lookup_fd_rcu(unsigned int fd)
return files_lookup_fd_rcu(current->files, fd);
}
+struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd);
+
struct task_struct;
struct files_struct *get_files_struct(struct task_struct *);
